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I don't know whether 6% droop in single shaft combined cycle is "standard" or not. I was not closely involved in that type of setting once I got into combined cycle control - it is done by the gas turbine controls engineering organization. I know the 4% setting was most common on simple cycle...

The easiest way to disable the preselected load control is for the operator to give a momentary load RAISE or LOWER command. It will put the load control in manual mode, where it will stay until a subsequent command to go to preselected load control or BASE load control. If you need to do...

The HP drum pressure is limited, rather than controlled, by the HP bypass pressure control and ultimately by the drum safety valves. Any minimum pressure control is via the steam turbine inlet pressure control, which usually just lets the steam turbine use all the steam available. The...

There is no technical reason against running 4-20 mA analog input and output signals in the same multicore cable. The only reason not to would be if there was some local code requiring separate cables.

A lot depends on your purchase documents. Did you specify the equipment and if so, did you specify the documentation to be provided? Who is responsible for the start up of the equipment? If it is not the fabricator, then they should have to provide whatever support is necessary to safely start...

You didn't say what the control system is. You also didn't say whether this is single shaft or multishaft combined cycle. If it is GE ICS (Mark VI or MarkVIe), then the temperature matching signal from the steam turbine is transferred over the UDH to one of the BOP or HRSG controllers. For GE...

If there is filter fouling it will increase the compressor inlet DP reading. Note, there may be 2 different sensors on the inlet, the 2nd one being called "compressor bellmouth DP" - I don't remember the actual difference between the two. You would have to look at the piping schematic to...

Trip instantly cuts off the fuel to the gas turbine. Protective shutdown initiates a "normal" shutdown sequence - unloading followed by fired shutdown. This is done where it is not necessary to stop the fuel flow instantly, but it is necessary to shut the machine down and not permit a restart...

On their heavy duty gas turbines, GE uses the seismic probes for protection and the proximity probes for monitoring and analysis. Their reasoning has been that on these machines, the mass of the rotor is nearly equal to the mass of the stator, and for this condition the seismic probes give a...

The compressor inlet DP sensor is used as part of the airflow calculation, not for filter fouling indication.

LCI is Load Commutated Inverter, and is used when the generator is also used as a starting motor. This arrangement is mainly used on 9F and 7F gas turbines. Do you have a stack closure to help bottle up the boiler? Closing this may also slow down the turning gear speed by reducing the natural...

The usual cause for an increase in exhaust pressure is an obstruction in the exhaust system. In your case, I would inspect the HRSG tubing in the exhaust duct - especially the superheater and reheater sections. You might also inspect the stack cover (damper) to make sure it is fully open (I know...

Bob, I fully agree with your comments about getting some expert advice. I have one comment on your "back of the envelope" type numbers: You may be a factor of 1000 too high in your estimate of the energy available. I believe "MSCF" is 1,000 SCF (not 1,000,000 SCF). So 80,000 SCF is about...

If it is a GE frame 6, the IGV's are modulated. If it is simple cycle, they may effectively be 2-position - full open or full closed (or maybe 3-position, 34 degrees, 57 degrees or 84 degrees).

The exhaust temperature measurement on a GE gas turbine is total temperature. (The thermocouple probes are in the exhaust gas stream, which will give you total temperature.)

> ALso, our PLC control system is not Mark IV but Speedtronic systems. Frame 6B (MS6001B) All MS6001B GE gas turbines use a GE Speedtronic control system. It may be Mark IV, Mark V, Mark VI or Mark VIe, or MAYBE Mark II. The first MS6001 was built before the controls shifted from Mark II to...

It depends on what the DCS is doing to calculate the flow from this signal. Most DCS will convert the 4-20 ma input signal to some value in some engineering units. If the feedwater flow is not compensated for temperature, and the only DCS calculation is to take a square root of the DP signal it...

> what is a mach number? Mach number is the ratio of the actual fluid velocity to the velocity of sound in that fluid medium at the flowing conditions.

It is not completely clear which machine is DROOP and which is ISOCH. Normal effect of running 2 machines in parallel and islanded is the DROOP machine will load up fully and the ISOCH machine will take the load swings. In that scenario, I would expect that GT-1 is ISOCH and GT-2 is DROOP, from...

If your concern was failure of one of redundant transmitters, you should get a "high deviation" alarm when one transmitter differs from the other 2 by a significant amount. I don't remember what the settings are, but you can find them in the GE control specification.